Several polymerization catalysts are known that are used for manufacture of polyolefin. Recently, group IV metals based FI catalysts (Fujita catalyst which is a phenoxy-imine based catalyst) with or without support are being widely used in the manufacture of polymers of different characteristics.
An FI catalyst is a heteroatom-coordinated early transition metal complex that combines a pair of non-symmetric phenoxy-imine [O−, N] chelating ligands with a group IV transition metal. The catalytically active species derived from FI catalysts is highly electrophilic and can assume up to five isomeric structures based on the coordination of the phenoxy-imine ligand. In addition, the accessibility of the ligands of the FI catalysts and their amenability to modification offers an opportunity for the design of diverse catalytic structures.
FI Catalysts when used in conjunction with suitable co-catalysts exhibit unique polymerization catalysis. Some of the distinct advantageous features of FI catalyst when used along with appropriate co-catalysts include precise control of product molecular weights, highly iso-specific and syndio-specific propylene polymerization, regio-irregular polymerization of higher α-olefins, highly controlled living polymerization of both ethylene and propylene at elevated temperatures, and precise control over polymer morphology. Many of the polymers that are available via the use of FI catalysts were previously inaccessible through other means of polymerization.
Polymerization of propylene or ethylene or copolymer of propylene and/or ethylene with other co monomers like conjugated diene in the presence of FI catalysts have been disclosed in U.S. Pat. No. 6,995,229, U.S. Pat. No. 6,838,540, U.S. Pat. No. 6,875,718, U.S. Pat. No. 6,462,136 and EP0874005. The FI catalysts disclosed in these patents are of both types, unsupported as well as the supported ones. The supported FI catalysts disclosed in some of these patents are directly supported. However, none of the catalysts comprise a phenyl ring with 5 fluoro substitutions that is attached to the N— of imine.
Preparation of syndiotactic polypropylene or its copolymer with ethylene or copolymer of alpha-olefins and conjugated diene in presence of FI catalyst where —N of imine is attached to —C6F5 group is described in U.S. Pat. No. 6,562,930, U.S. Pat. No. 6,787,624, U.S. Pat. No. 7,268,243 and U.S. Pat. No. 7,119,154. The FI catalysts disclosed in all these patents however are unsupported.
The hitherto known FI catalysts are either not immobilized or immobilized directly (physically) on the inorganic support which usually affects the catalyst efficiency.